Three-position solenoid actuated switch

ABSTRACT

A solenoid switch having first and second closed positions with an open position therebetween. A center-tapped coil is wound about a core capable of conducting a magnetic field. Direct current of one polarity is applied between the center tap and one coil end; direct current of the same polarity is applied between the center tap and opposite end. A three-position reed switch having a permanent magnet attached thereto is positioned adjacent the core. By the expedient of providing a reference impedance in series with the direct current between the center tap and one end of the coil and a comparison impedance between the center tap and the other end of the coil, the reed switch can be moved to any of its three positions.

United States Patent [72] Inventor Frank E. Gray 2070 Lathan St. #10,Mountain View, Calif. 94040 [21] Appl. No. 876,512 [22] Filed Nov. 13,1969 [45] Patented Mar. 23, 1971 [54] THREE-POSITION SOLENOID ACTUATEDSWITCH 10 Claims, 3 Drawing Figs.

[52] U.S. Cl 317/150, 335/78, 310/674 [51] Int. Cl ..l-l0lh 51/22 [50]Field oi'Search 317/150, 123; 335/78, 177, 179, 153, 205; 310/674;307/115, 116, 117, 125, 143

[56] References Cited UNITED STATES PATENTS 3,043,932 7/1962 Morris317/150 Attorney-Townsend & Townsend ABSTRACT: A solenoid switch havingfirst and second closed positions with an open position therebetween. Acentertapped coil is wound about a core capable of conducting a magneticfield. Direct current of one polarity is applied between the center tapand one coil end; direct current of the same polarity is applied betweenthe center tap and opposite end. A three-position reed switch having apermanent magnet attached thereto is positioned adjacent the core. Bythe expedient of providing a reference impedance in series with thedirect current between the center tap and one end of the coil and acomparison impedance between the center tap and the other end of thecoil, the reed switch can be moved to any of its three positions.

PATENTEU MR2 319m SHEET 1 BF 2 INVENTOR.

FRANK ELLIS GRAY FlG 2 ATTORNEYS THREE-PDSETEON SDLENOHD ACTHJA'EEDSWllTClii This invention relates to solenoid switches and in particularto a solenoid switch having first and second closed positions with anopen position therebetween.

Solenoid switches are frequently used in dual combinations to provideadjustment or positioning of thermostatic or rotary devices. Forexample, in many thermostat devices, one solenoid is used to actuate aheater when temperatures are too cool; another solenoid is sued toactuate a cooler or air conditioner when temperatures are too warm. Asanother example, in many rotary devices, one solenoid system is used toactuate rotation in one direction; another solenoid system is used toactuate rotation in an opposite direction.

In such dual solenoid systems, two disadvantages occur. First, there isa duplicity of coils, magnetically moved members and electricalcontacts. Secondly, there is an ever present danger that pairedsolenoids will either be inadvertently actuated, lock, or jam to causetheir connected devices to work in opposition to one another. In thecase of a heater and air conditioner controlled by such dual solenoids,both the heater and air conditioner can be caused to work at the sametime. in the case of a rotary control, the dual solenoids canmalfunction to signal for rotation in both directions at the same time.Unfortunately, providing such systems with fail-safe connections toprevent such inadvertent opposing actuation, complicates such dualsolenoid switch systems to the point where they are not practical.

Accordingly, an object of this is to provide a three-position solenoidswitch having first and second electrically closed positions with aneutral position therebetween. A centertapped coil is wound about a corecapable of conducting a magnetic field. By the expedient of seriallyconnecting variable impedances in direct current circuits of oppositepolarity between the center tap and each of the core a North-Southpolarity to a South-North polarity. A A reed switch is placed adjacentthe core and the deflected reed of the switch provided with a magnetwhich can be repelled and attracted relative to the magnetic fieldemanating from the conductive core. When either the North-South orSouth-North magnetic field predominates, the reed is deflected to one oftwo closed positions; when the fields balance, the reed assumes aneutral position therebetween.

An advantage of this single solenoid switch is that it can be used tosupplant conventional dual solenoid systems.

A further advantage of this switch is that as only one reed switch isused, the possibility of the dual functions of the control beingactuated in opposition to one another is eliminated.

An additional object of this invention is to disclose a solenoid havingtwo coil segments for producing opposing magnetic fields and a reedswitch which is responsive to the predominating magnetic field only.

An advantage of these opposing magnetic fields is that the intensity ofthe magnetic fields produced by the coil segments are effectivelycompared, and the reed switch actuated by the predominating magneticfield only.

A further advantage of this invention is that even though the respectivecurrent flow in the coil segments vary considerably, the reed switchwill only respond to the predominating magnetic field.

A further object of this invention is to disclose in combination withthe three-position solenoid switch, a control for positioning rotarydevices, which control does not include expensive master and slavearmatures.

Other objects, features and advantages of this invention will becomemore apparent after referring to the following specification andattached drawings in which:

lFlG. i is a schematic view of the solenoid switch of this inventionillustrating the placement of the center-tapped coil relative to anactuated reed switch;

H6. 2 is a schematic wiring diagram similar to HO. 1 illustrating apreferred winding of the coil segments for actuating the reed switch;and,

lF-lG. 23 illustrates the use of the three-position solenoid switch ofthis invention for the control of a rotating television antenna.

With reference to FIG. ll, core A is shown having a centertapped coil Bwound thereabout. Direct current sources C of the same polarity provideopposing coil currents between each of the coil ends and an intermediatecenter tap. Connected in series with the direct current sources C aretwo variable impedances D.

As can be seen, when the impedance D and the current source C connectedbetween one coil end and center tap varies with respect to the otherimpedance D and the other current source C connected between the othercoil end and center tap, core A will receive magnetic fields of oppositepolarities and differentintensities. For example, where the respectivecurrent sources C are of equivalent outputs and the left-hand impedanceD is lower than the right-hand impedance D, center-tapped coil B willinduce in core A a South- North polarity; alternately, where theright-hand impedance is less than the left-hand impedance, center-tappedcoil B will induce in the core A a North-South polarity.

The magnetic field within core A operates to position reed switch Eadjacent the end of the core. The central reed 16 of reed switch E hasaffixed to the end thereof a small permanent magnet F having a polarityaligned parallel to the longitudinal axis of the core. When the core isof a South-North polarity, the South-North position of the magnet F onreed switch E causes the switch to close toward core A connecting theinput of the reed switch to output number 1. Alternatively, when theNorth-South polarity of core A predominates, magnet F on reed switch Ewill be repelled away from core A, connecting the input of the reedswitch to-output number 2. As is apparent, where the respective magneticfields of core A cancel one another, magnet F will neither be attractednor repelled and reed switch E will assume a neutral position betweenthe respective outputs causing an open circuit.

Core A is typically constructed of a material which will not retainmagnetic polarity. Moreover, the core is either of laminated soft ironconstruction or alternately of powdered iron construction so as toprovide a barrier against generation of heat inducing eddy currentstherein. I Coil B has a helical winding of conventional insulated copperwire. This wire, wound from one end of core A to the opposite end ofcore A, is maintained equidistant with respect to the central axis ofthe core. At the approximate center of coil B, the coil is centertapped.

Regarding power supplies C, it is essential in the practice of thisinvention that power supplied to the coil be a direct current. Moreover,the magnetic field produced by the current between the center tap of thecoil and one of its ends must always be opposite to the magnetic fieldproduced by the current between the center tap and the other coil end.

Voltage supplies C used for this purpose can be virtually any type of DCpower supply. As here illustrated, they are in the form of batteries.Alternately, a conventional DC power supply or supplies can be used.

impedances D can be of any variety. As shown in the schematic of FIG. 1,the impedances are produced by variable resistors or pots. Alternately,virtually any type of electrical resistance which will produce avariable impedance can be utilized. Typically, one or more of theseresistors is connected so as to be operatively changed in impedance bythe changing state of a control apparatus. Such connections, being wellunderstood, are not shown in FlG. 1.

Reed switch E is of conventional configuration. Typically, fourdielectric wafers 12 are maintained and clamped in coaxial relation on ashaft M with three metallic reeds l6 captured therebetween. As hereshown, each of the metallic reeds 16 consists of a nonmagnetic elasticmaterial and extends outwardly from the wafers l2 to a position wherethe ends of each reed 16 are aligned coaxially to the longitudinal axisof core A.

The ends of the respective reeds in are provided with electricalcontacts. Typically, the two reeds 16 of switch E have copper coatedwafers 20 attached thereto. These wafers are attached to theirrespective reeds so as to face inwardly and towards the central reed l6.

Central reed 16 has permanent magnet F attached thereto with itsNorth-South field being substantially parallel to the axis of the core.This magnet, usually of an iron nickel alloy, is dipped in copper andthereafter silver tipped so as to provide an electrical contactingsurface of high conductance.

The electrical switching connections of the solenoid are made throughcontact between the individual reeds. Typically, central reed 116 isconnected to the input of the solenoid. The two outside reeds areconnected to the respective outputs of the solenoid. As here shown, theoutside reed 16 nearest core A is connected to output l. The outsidereed furthest removed from core A is connected to output 2. Deflectionof central reed 116 by the magnetic field of core A towards core A willcause a closed circuit between the input and output 1. Conversely,deflection of central reed l6 away from core A will cause a closedcircuit between the input and output 2. Where the respective magneticfields of core A are balanced and no magnetic field exists, central reed16 will be in the neutral, undetlected position and the circuits betweenthe input and outputs ii and 2 will be open.

The configuration of the coil B on core A as illustrated in FIG. ll hasone disadvantage. It will. be noted that the righthand segment of coil Bbetween the center tap and end is closer to reed switch E than theleft-hand segment of coil B between the center tap and its respectiveend. Such a closer proximity of the right-hand segment of the coil toreed switch E permits the magnetic field generated therein to beconducted along a shorter segment of core A and to be communicated toreed switch E with fewer losses. As is apparent, this effect can becompensated for by reducing the number of winds on the right-handsegment relative to the number of winds on the left-hand segment of coilB. This reduction in the number of windings, however, has thedisadvantage in that each switch produced according to this inventionwill require individual adjustment of its center tap.

Referring to FIG. 2, a configuration of the coil which does not requireindividual adjustment of its center tap is illustrated. Coil B,illustrated in FIG. 2 comprises two helical windings 25 and 26.Typically, the two strands of the windings are simultaneously wound inside-by-side relation from one end of core A to the opposite end of coreA. Both strands are given an equal number of windings about the core.Winding 25 is connected to first impedance D at one end of the pairedwindings.

At the opposite end of the paired windings, winding 25 is connected toground. Winding 26 is connected to second impedance D at an end of thecoil opposite to the point of connection between winding 25 and thefirst impedance D. At the opposite end, winding 26 is connected toground. Thus it will be seen that winding 25 produces a magnetic fieldwhich opposes the magnetic field produced by winding 26.

The advantage of coil B, can be readily understood. Each winding 25 and26 will extend over the same length of core A. Furthermore, core A willbe required to conduct the magnetic field of each coil the same distanceto reed switch E. Thus, no individual balancing of the coil lengthbetween the center tap and each of the coil ends is required in theembodiment of this solenoid as illustrated in FIG. 2..

it will be noted that the embodiment illustrated in FIG. 2 utilized onlyone direct current source C. As is apparent, this invention can utilizeeither a single current source or paired current sourcesone sourceconnected to each coil segment.

The utility of the apparatus herein illustrated is believed apparent.One use of the solenoid herein illustrated has been found in the controlof the rotation of a directional television antenna, as illustrated inFIG. 3. 3.

Referring to FIG. 3, a solenoid switch comprising a core A,center-tapped coil B and direct current power supplies C is shownconnected in combination with a counterwound motor G to effect remotedirectional control of a television antenna 30. The directional controlof antenna 30 is effected by the impedances Di and D2 connected acrossthe center-tapped coil B.

The impedance D1 is connected in series with DC power supply C and theright-hand segment of center-tapped coil B. Positioning of the variableresistance of coil D1 permits the right-hand segment of coil B to have areference magnetic field imparted thereto.

Impedance D2 is connected to and varied by the rotation of shaft 35 ofcounterwound motor G. As shaft 35 of counterwound motor G moves with therotation of antenna 3b, impedance D2 will vary.

To effect rotation of counterwound motor G. the motor is connected to analternating current source 40. Typically, one line of the alternatingcurrent source 410 is connected directly to one winding of counterwoundmotor G. The remaining line of the alternating current source isconnected to the central reed 16 of reed switch E.

The operation of the antenna rotating circuit illustrated in FIG. 3 canbe readily understood. Typically, impedance D1 is varied so as tounbalance the magnetic field generated through coil B. Thereafter, reedswitch E will be deflected to connect the alternating current of ACpower supply 40 through one winding or the other winding of counterwoundmotor G. When central reed 16 of reed switch E is deflected away fromcore A, the upper winding of counterwound motor G will be actuatedcausing antenna 30 to rotate in a counterclockwise direction.Alternately, when central reed lb of reed switch E is deflected towardscore A, the lower winding of counterwound motor G will be actuated,causing counterwound motor G to rotate antenna 30 in a clockwisedirection. As is apparent, a television viewer can effect remoterotation of the antenna 30 by positioning impedance Dl untilcounterwound motor G causes impedance D2 to match impedance D1,deflecting reed switch E to the neutral position.

It will be apparent, that positioning of antenna 30 could be provided byone or more impedances DI. For example, individual impedance D1 could beconnected to a television channel selector. In each position of thetelevision channel selector, the individual impedances D1 could be tunedfor the optimum antenna position. With such an arrangement, when thechannel selector was moved, the antenna 30 would be caused to rotate tothe optimum pretuned position for each channel, thus effecting automaticantenna rotation without individual adjustment of the antenna by theviewer.

In the construction of this switch, it is important that it be isolatedfrom ambient magnetic fields which could position the reed switchinadvertently. As the construction of such magnetic shielding is wellunderstood, it will not be described herein.

Other applications in which the apparatus of this invention could beuseful are believed apparent. For instance, in a thermostatic controlwherein both an air conditioner and a heater are controlled, thesolenoid could be of great use. In one position between the input andone of the outputs, the solenoid could actuate the air conditioner. Inanother position between the input and the remaining output the solenoidcould actuate a heater. In the neutral position neither the airconditioner nor the heater would be actuated and the temperature wouldbe the desired temperature. Changes in the desired temperature, ofcourse, could be effected by varying one of the impedances. Likewise,while several embodiments of this invention have been shown anddescribed, it will be apparent that other adaptations and modificationsof this device can be made without departing from the true spirit andscope of this invention.

1 claim:

1. In a control system having a first impedance for indicating a desiredcontrolled state and a second impedance for indicating the actual stateof said system, the combination with said first and second impedancescomprising: first and second coil segments wound about a common axis forinducing magnetic fields upon current flowing therethrough; at least onedirect current supply means; a switch adjacent one end of said coilsegments having a moving member thereof emanating a magnetic fieldpolarized in axial alignment substantially parallel to the axialalignment of the fields of said coil segments,

said moving member being movable towards and away from said coilsegments between at least two positions for said switch; connectingmeans for connecting one output of said direct current supply means forconnecting one output of said direct current supply means to one end ofsaid coil segments and the other output of said direct currentgenerating means to the opposite end of said coil segments, each saidconnections to each said segments being in series with one of saidimpedances to produce opposing magnetic fields in said coil segmentsresponsive to variations in said impedances, whereby said deflectablemember of said switch will be positioned responsive to the predominatingmagnetic field of said coil segments.

2. The invention of claim 1 and wherein said switch comprises a reedswitch having a deflectable reed; said reed having a permanent magnetattached thereto, which magnet emanates a magnetic field polarizedaxially to the axial length of said coil segments.

3. The invention of claim 1 and wherein said movable member is movableto an open position between said two closed positions.

4. The invention of claim 1 and wherein said coil segments are wound inhelically side-by-side relation.

5. The invention of claim 1 and wherein said coil segments are woundabout a core for conducting the magnetic field produced by said coilsegments.

6. in combination: first and second coil segments wound about an axisfor inducing magnetic fields polarized along said axis; at least onedirect current generating means; first means connecting said directcurrent generating means to one coil segment for providing a magneticfield of a first polarity, and

second means connecting said direct current generating means to theother segment of said coil for providing a magnetic field of reversepolarity; a switch positioned in the magnetic fields of said coilsegments, said switch including a movable member having motion towardsand away from at least one electrically closed position positioned oneither side of said deflectable member; a permanent magnet on saidmovable member of said switch having its North-South field axis alignedsubstantially parallel to the magnetic fields of said coil; a referenceimpedance connected in series with said connecting means and directcurrent generating means for producing a first current flow in one ofsaid coil segments; and a comparison impedance connected in series withsaid connecting means and said direct current generating means forproducing a second current flow in the other of said coil segmentswhereby said movable member of said switch will be deflected towards andaway from said coil by the predominating magnetic field generated insaid coil by said first and second currents.

7. The combination of claim 6 and wherein said switch is movable betweenan open position and two closed positions.

8. The invention of claim 6 and wherein said coil segments are providedfrom a single coil center-tapped.

9. The invention of claim 6 and wherein said switch comprises a reedswitch having a deflectable reed with said magnet attached thereto.

10. The invention of claim 6 and wherein said coil segments are woundabout a core for conducting the magnetic fields produced in said coilsegments.

1. In a control system having a first impedance for indicating a desiredcontrolled state and a second impedance for indicating the actual stateof said system, the combination with said first and second impedancescomprising: first and second coil segments wound about a common axis forinducing magnetic fields upon current flowing therethrough; at least onedirect current supply means; a switch adjacent one end of said coilsegments having a moving member thereof emanating a magnetic fieldpolarized in axial alignment substantially parallel to the axialalignment of the fields of said coil segments, said moving member beingmovable towards and away from said coil segments between at least twopositions for said switch; connecting means for connecting one output ofsaid direct current supply means for connecting one output of saiddirect current supply means to one end of said coil segments and theother output of said direct current generating means to the opposite endof said coil segments, each said connections to each said segments beingin series with one of said impedances to produce opposing magneticfields in said coil segments responsive to variations in saidimpedances, whereby said deflectable member of said switch will bepositioned responsive to the predominating magnetic field of said coilsegments.
 2. The invention of claim 1 and wherein said switch comprisesa reed switch having a deflectable reed; said reed having a permanentmagnet attached thereto, which magnet emanates a magnetic fieldpolarized axially to the axial length of said coil segments.
 3. Theinvention of claim 1 and wherein said movable member is movable to anopen position between said two closed positions.
 4. The invention ofclaim 1 and wherein said coil segments are wound in helicallyside-by-side relation.
 5. The invention of claim 1 and wherein said coilsegments are wound about a core for conducting the magnetic fieldproduced by said coil segments.
 6. In combination: first and second coilsegments wound about an axis for inducing magnetic fields polarizedalong said axis; at least one direct current generating means; firstmeans connecting said direct current generating means to one coilsegment for providing a magnetic field of a first polarity, and secondmeans connecting said direct current gEnerating means to the othersegment of said coil for providing a magnetic field of reverse polarity;a switch positioned in the magnetic fields of said coil segments, saidswitch including a movable member having motion towards and away from atleast one electrically closed position positioned on either side of saiddeflectable member; a permanent magnet on said movable member of saidswitch having its North-South field axis aligned substantially parallelto the magnetic fields of said coil; a reference impedance connected inseries with said connecting means and direct current generating meansfor producing a first current flow in one of said coil segments; and acomparison impedance connected in series with said connecting means andsaid direct current generating means for producing a second current flowin the other of said coil segments whereby said movable member of saidswitch will be deflected towards and away from said coil by thepredominating magnetic field generated in said coil by said first andsecond currents.
 7. The combination of claim 6 and wherein said switchis movable between an open position and two closed positions.
 8. Theinvention of claim 6 and wherein said coil segments are provided from asingle coil center-tapped.
 9. The invention of claim 6 and wherein saidswitch comprises a reed switch having a deflectable reed with saidmagnet attached thereto.
 10. The invention of claim 6 and wherein saidcoil segments are wound about a core for conducting the magnetic fieldsproduced in said coil segments.